Problem:
Show that there are infinitely many triples of positive integers such that
Problem:
Show that there are infinitely many triples of positive integers such that
Solution:
Note that is a solution. Now, fix , the original equation becomes
We see that by Vieta's theorem, taking (1) as a polynomial in , there are 2 solutions of , adding up to .
Thus, if then we have a new set of solutions: , which by symmetry gives as a bigger set of solutions in (non-strict in , strict in as ) when .
Since we can repeat this process infinitely, as increases they always fulfill the requirement that , thus we can generate infinitely many solutions.